The premise of “The Last Unicorn” is simple: DeBuys tagged along with biologist William Robichaud for a trek through the forests and waterways of central Laos searching for evidence of an extremely rare animal called a saola. Discovered by most of the world in 1992, saola share some of their DNA with wild cattle, but they are unique for the two horns, growing up to half a meter long, that extend from their head and sweep back over their body. Seen in profile, the horns merge into one, making the animal resemble the mythical beast that legend has it could only be glimpsed by the pure of heart.

DeBuys jokes that the legend disqualifies him, but writes that “blue Western eyes” like his have never gazed on a wild saola. And that was reason enough for him to team up with Robichaud and teams of local boys and men for a punishing trek over mountainous terrain and white-water rapids. The mission was multifold: to look for signs of the elusive animal, dismantle snares set by poachers and install camera traps in hopes of capturing an image long after the expedition was over.

The book unfolds as part travelogue, part adventure story and part conservationist screed. DeBuys is at his best in the first person. Here he is chronicling a perilous descent as he follows a native guide down a mountain: “Where he strides, I slide; where he ducks, I lurch. Reaching out to steady myself and check my momentum, I realize, too late, that the slender trunk I am about to grab bristles with thorns. … I lunge for a different sapling … surely a safe one — and sink my hand into a living skin of ants.”

Overall, the book will appeal to nonfiction readers who enjoy learning about flora, fauna and people in parts of the world they’ll likely never visit. It’s comforting to know there are people like Robichaud and writers like deBuys who are committed to sharing their stories. It’s even more comforting to know their efforts could result in helping preserve the wildness of this world and the survival of a species.